1. Field of the Invention
The invention relates to an extendible exhaust nozzle bell for a rocket engine of an aircraft or spacecraft which includes a first part having a smaller diameter fixedly arranged on the motor of the rocket engine and a second part having a larger diameter arranged in a flexible manner with respect to the first part. In this manner, in a front stowed position, the second part is located to surround the first part closer to the rocket motor and, in a rear operating position, to continue the first part and to be arranged further away from the rocket motor with a closed volume that can be acted on by a gaseous fluid. The volume when acted on by the gaseous fluid under enlargement of the volume causes an extension of the second part of the exhaust nozzle bell from the stowed position into the operating position.
2. Discussion of Background Information
An extendible exhaust nozzle bell for a rocket engine is known from U.S. Pat. No. 4,706,886, which comprises a first part with smaller diameter fixedly arranged on the motor of the rocket engine and a second part with larger diameter arranged in a flexible manner with respect to the first part, whereby in a front stowed position (with respect to the flight direction of the aircraft or spacecraft) the second part is located surrounding the first part closer to the rocket motor and in a rear operating position (relative to the flight direction, continuing the first part, is arranged further away from the rocket motor. A closed volume that can be acted on by a gaseous fluid, which volume when acted on by the gaseous fluid under enlargement of the volume causes an extension of the second part of the exhaust nozzle bell from the stowed position into the operating position. With the known exhaust nozzle bell, this closed volume is provided by an essentially cylindrical bellows with an annular cross section which is arranged inside the exhaust nozzle bell. In the stowed position these bellows are folded together flat and when acted on with the gaseous fluid are unfolded in the axial direction of the rocket engine and thus cause an extension of the second part of the exhaust nozzle bell from the stowed position into the operating position. After the operating position has been reached in which the second part of the exhaust nozzle bell has been locked to the first part of the exhaust nozzle bell by a locking mechanism, the bellows are released and jettisoned from the second part of the exhaust nozzle bell by corresponding release mechanisms provided especially for this. A disadvantage in the known extendible exhaust nozzle bell is a relatively complicated structure of the bellows and the said release mechanisms which is associated with a high weight. Furthermore, due to the complicated structure there is a certain danger of a defective function.